The method of RDE and RRDE measurements was used to investigate the characteristics and the mechanism of the anodic oxidation of iodide-mediated sulfur dioxide solution. The intermediate products such as iodine and iodate were detected and the catalytic reaction mechanism which was composed of the electrochemical oxidation of iodide and the chemical reaction between sulfur dioxide and oxidized products was disclosed. The limiting current was increased with the increase of rotation speed of disk electrode which brought aobut the rapid reaction of iodine removal. The electrochemical oxidation of sulfur dioxide did not nearly occur. The collection efficiency in the electrochemical reaction of iodide-mediated sulfur dioxide solution was greatly lower than that in the electrochemical reaction of iodide and increased with the increase of rotation speed of electrode, which confirmed the catalytic reaction mechanism.